Physiochemical and antibacterial analysis of gelatin–chitosan edible film with the addition of nitrite and garlic essential oil by response surface methodology

The mechanical properties of edible films upon variation of gelatin (G) and chitosan (C) concentration (G%/C%) were compared using constrained mixture and response surface methodology (RSM) and their antibacterial activities against P. aeruginosa, B. cereus, and L. monocytogenes by the addition of sodium nitrite and garlic essential oil (GEO) were analyzed. Both methods show that increasing chitosan concentration will gradually enhance edible film tensile strength but decrease their elongation at break. Optimization to find the gelatin–chitosan edible film with the maximum elasticity was performed by minimizing the Young’s modulus which yields a value of 0.41 MPa corresponding to a G60/C40 gelatin–chitosan concentration using constrained mixture and 0.31 MPa corresponding to a G76/C24 gelatin–chitosan concentration using the RSM method. Antibacterial analysis of the edible film showed that the addition of sodium nitrite and GEO in gelatin–chitosan edible film enhances their antibacterial activity significantly and increasing the GEO concentration also improve the antibacterial activity of the film. Practical applications The outcome of our work has practical applications in the field of biodegradable edible film, for example, for environmentally friendly meat coatings due to its optimum elasticity property. In addition, our gelatin–chitosan film with garlic essential oil also exhibits significant antibacterial properties which can compete with commercial film that uses nitrite addition and therefore prolong the shelf life of the food without the risk of carcinogenic effects. From the potential point of view, our work should stimulate more research toward the development and optimization of biodegradable edible films with noncarcinogenic antibacterial properties.